Physical properties of a polymer are affected mostly by a structure of a polymer, along with a molecular weight and an extent of molecular weight distribution. The simplest polymer structure is a linear structure. A linear structure literally refers to a shape in which a monomer that forms a polymer is bonded linearly to constitute a main chain. Various types of branched chains are possible, and side chains may be formed. These side chains can affect the physical properties of a polymer.
Of the above side chains, a long chain branch (LCB) may affect the strength of a polymer, the glass temperature, or the like.
Meanwhile, of the above side chains, an atactic short chain branch may reduce the strength of a polymer, since it makes a polymer arrangement poor.
It is thus important in analyzing the characteristics of physical properties of a polymer to identify the existence of side chains, which greatly affect physical properties of a polymer, and to accurately measure the number thereof.
The number of side chains that branches in a polymer may be measured through the linear correlation of a log scale graph of the molecular weight and the intrinsic viscosity, which is obtained by analyzing the polymer. In a log scale graph of the molecular weight and the intrinsic viscosity of a polymer having side chains, there is a critical point representing a maximum straight-line segment, to which the slope is constant as a straight line from the origin as in the graph of a linear polymer, and after which the slope decreases at a certain point. The more side chains exist within a polymer, the greater the difference in slope from the log scale graph of a linear polymer after a critical point representing a maximum straight-line segment.
Generally, as a method for computing the number of side chains of a polymer having side chains, the number of side chains of a polymer is computed using an area generated based on the difference from a reference graph after a critical point by comparing a log scale graph of a polymer having side chains with a log scale graph of a linear polymer as a reference.
At this time, accurately locating a critical point representing a maximum straight-line segment is important in order to compute the number of side chains of a polymer with high accuracy.